1. Field of the Invention
The present invention relates to an image pick-up apparatus for thinning out (decimating), at a predetermined interval, a plurality of image frames outputted from a camera for taking and outputting pictures as a first predetermined number of frames per second so as to output a second predetermined number of image frames per second, the second predetermined number being smaller than the first predetermined number.
2. Description of the Related Art
Of various image pick-up systems expected to be used in digital broadcasting in the United States of America, the 30P system which handles about 30 frames per second without interlace has been attracting much attention from public because it is capable of realizing such a digital broadcasting at a very low cost by employing a part of conventional broadcasting system. However, according to this 30P system, in an picture having a large motion, slightly unnatural motions are produced because its frame frequency is low. Additionally, a 60P system camera which fetches actual images at a rate of 60 frames has been recently developed.
As described above, the 30P system has such a disadvantage that although this system is achieved at a very low cost, in a picture having a large motion, slightly unnatural motions are produced because its frame frequency is low.
Accordingly, it can be considered to use a 60P system camera which is capable of outputting images equivalent to when an interlace is provided, for a picture having a large motion and realize the 30P system by utilizing an output of the 60P system camera so as to produce a smooth motion for the picture having a large motion.
The present invention has been achieved in views of the above and an object of the invention is to provide an image pick-up apparatus capable of obtaining a natural image smooth in motion for even a picture having a large motion despite use of the 30P system.
To achieve the above object, there is provided an image pick-up apparatus for thinning out, at a predetermined interval, a plurality of image frames outputted from a camera for taking and outputting pictures as a first predetermined number of frames per second, so as to output a second predetermined number of image frames per second, the second predetermined number being smaller than the first predetermined number, the image pick-up apparatus comprising: delaying means for delaying an invalid frame just before and picked out by a single frame relative to each of the second predetermined number of valid frames; subtracting means for computing a differential between the delayed invalid frame and a corresponding valid frame; filtering means for picking out only a portion over a predetermined value of the differential outputted from the subtracting means; attenuating means for attenuating the level of the portion of the differential picked out by the filtering means to xc2xd; and adding means for adding the attenuated portion of the differential to the corresponding valid frame.
According to the present invention, an invalid frame just before a valid frame and picked out is delayed by a single frame and then a differential between the delayed invalid frame and the valid frame is computed. Of the differential, only a portion over a predetermined value is picked out and the picked out differential level is attenuated to xc2xd and then added to the valid frame. Therefore, an image of the invalid frame just before and picked out is superimposed on a 30P image, so that for even a picture having a large motion, smooth and natural images can be obtained.
Further, to achieve the above object, there is provided an image pick-up apparatus for thinning out, at a predetermined interval, a plurality of image frames outputted from a camera for taking and outputting pictures as a first predetermined number of frames per second, so as to output a second predetermined number of image frames per second, the second predetermined number being smaller than the first predetermined number, the image pick-up apparatus comprising: delaying means for delaying an invalid frame just before and picked out by a single frame relative to each of the second predetermined number of valid frames; subtracting means for computing a differential between the delayed invalid frame and a corresponding valid frame; a 2-dimensional low pass filter for conducting 2-dimensional low pass filtering processing on the differential output from the subtracting means; filtering means for picking up only a portion over a predetermined value of the differential subjected to the 2-dimensional low pass filtering processing by the 2-dimensional low pass filter; attenuating means for attenuating the level of the portion of the differential picked up by the filtering means to xc2xd; and adding means for adding the attenuated portion of the differential to the corresponding valid frame.
According to the present invention, an invalid frame just before a valid frame and picked out is delayed by a single frame and then a differential between the delayed invalid frame and the valid frame is computed. This differential is, subjected to the 2-dimensional low pass filtering processing, and of the differential, only a portion over a predetermined is picked out and this picked out differential level is attenuated to xc2xd. This attenuated differential level is added to the valid frame. As a result, the image of the invalid frame just before and picked out is superimposed on the 30P image so that for even a picture having a large motion, smooth and natural images can be obtained. Specifically because detection of an image having a small motion is canceled by the 2-dimensional low pass filtering processing, further natural images can be obtained.
Further, to achieve the above object, there is provided an image pick-up apparatus for thinning out, at a predetermined interval, a plurality of image frames outputted from a camera for taking and outputting pictures as a first predetermined number of frames per second, so as to output a second predetermined number of image frames per second, the second predetermined number being smaller than the first predetermined number, the image pick-up apparatus comprising: delaying means for delaying an invalid frame just before and picked out by a single frame relative to each of the second predetermined number of valid frames; subtracting means for computing a differential between the delayed invalid frame and a corresponding valid frame; a 2-dimensional low pass filter for conducting 2-dimensional low pass filtering processing on the differential output from the subtracting means; filtering means for picking up only a portion over a predetermined value of the differential subjected to the 2-dimensional low pass filtering processing by the 2-dimensional low pass filter; attenuating means for attenuating the level of the portion of the differential picked up by the filtering means to a range of 0-xc2xd; and adding means for adding the attenuated portion of the differential to the corresponding valid frame.
According to the present invention, the invalid frame just before the valid frame and picked out is delayed by a single frame and a differential between the delayed invalid frame and the valid frame is computed. This differential is subjected to the 2-dimensional low pass filtering processing and then, of the differential, only a portion over a predetermined value is picked out and the picked out differential level is attenuated to a range of 0-xc2xd and added to the valid frame. As a result, the invalid frame just before and picked out is superimposed on the 30P image so that for a picture having a large motion, smooth and natural images can be obtained. Specifically by attenuating the differential level to a range of 0-xc2xd, even if a moving image is stopped suddenly, a natural image can be obtained.
Further, to achieve the above object, there is provided an image pick-up apparatus for thinning out, at a predetermined interval, a plurality of image frames outputted from a camera for taking and outputting pictures as a first predetermined number of frames per second, so as to output a second predetermined number of image frames per second, the second predetermined number being smaller than the first predetermined number, the image pick-up apparatus comprising: first delaying means for delaying each of the second predetermined number of valid frames by a frame; second delaying means for delaying an invalid frame just before and picked out relative to each of the valid frames; adding means for adding an invalid frame just after and picked out relative to each of the valid frames and the invalid frame delayed by two frames by the second delaying means; averaging means for averaging a sum of the two invalid frames outputted from the adding means; subtracting means for computing a differential between the averaged sum of the two invalid frames and the valid frame delayed by a frame by the first delaying means; a 2-dimensional low pass filter for conducting 2-dimensional low pass filtering processing on the differential output from the subtracting means; filtering means for picking out only a portion over a predetermined value of the differentials subjected to the 2-dimensional low pass filtering processing by the 2-dimensional low pass filter; attenuating means for attenuating the level of the portion of the differential picked out by the filtering means to a range of 0-⅔; and adding means for adding the attenuated portion of the differential to the valid frame.
According to the present invention, the valid frame is delayed by a single frame and the invalid frame just before the valid frame is delayed by two frames. The invalid frames just after and before the valid frame are summed up and averaged. A differential between this averaged invalid frame and the valid frame is computed and this differential is subjected to the 2-dimensional low pass filtering processing. Only a portion over a predetermined value is picked out and this picked out differential level is attenuated to a range of 0-⅔ and the attenuated differential level is added to the valid frame. As a result, the averaged image of the invalid frames picked out and just before and after is superimposed on the 30P image, so that for even a picture having a large motion, smooth and natural images can be obtained. Specifically unnaturalness caused when a moving image is stopped suddenly can be eliminated.